Generalized vitiligo (GV) is the most common pigmentary disease, with progressive patches of white skin and hair resulting from chronic autoimmune destruction of melanocytes in the involved regions. This project runs parallel to our genetic project which is aimed at discovering the genetic architecture underlying GV, with a highly successful genomewide association study (GWAS) providing the beginning of a parts list for the disorder. This current project is aimed at carrying out functional analyses of specifc genes, proteins, and even specific genetic variants that appear potentially causal for GV. This project thus represents the beginning of a new era in GV functional biology, with functional studies targeting specific hypotheses driven by the specific results of our robust genetic studies of underlying pathobiology. Most GV susceptibility genes thus far identified play various roles in the immune response. For some, the functions are only vaguely understood and cannot yet be approached by specific functional analysis. This project will first address genes for which we already know enough biology to formulate relevant hypotheses and devise appropriate assays, including NLRP1, TYR, HLA-A, and IL2RA. For some, the hypotheses can be very specific, testing the biological effects of specific, already-identified gene variations that are potentially causal for disease liability, an approach that has already borne fruit in our current studies of NLRP1 which suggest possible new avenues of treatment based on blocking the IL-1b and downstream pathways. Thus, the studies proposed here represent a new dawn of vitiligo functional biology, driven by knowledge of specific genes, specific gene variations, specific biological pathways, and specific biological hypotheses based on that knowledge. Our genetic studies of GV have already revised current clinical practice guidelines. Our hope and anticipation is that pairing of our genetic studies with directed functional studies of the corresponding proteins, variants, and pathobiological pathways will provide key information that may culminate in the development of new treatments specifically directed against these proteins and pathways. PUBLIC HEALTH RELEVANCE: This project aims to carry out functional studies of genes responsible for generalized vitiligo (GV), an autoimmune disease that is the most common pigmentary disorder and which has high impact on persons of color. Our genetic studies, carried out under a parallel project, have begun to elucidate the genetic architecture underlying GV, providing the beginning of a parts list for the disorder. This project will analyze the specific functions of several of those genes, the corresponding proteins, and even specific genetic variants of those genes. This project thus represents a new era in GV biology, with functional studies targeting hypotheses based on robust genetic analyses of underlying pathobiology. The proposed studies will provide key information that may culminate in the development of new treatments specifically directed against these proteins and pathobiological pathways.